This invention relates generally to single or multi-pole circuit breakers, and more particularly to circuit breakers having improved arc chambers.
The basic functions of circuit breakers are to provide electrical system protection and coordination whenever abnormalities occur on any part of the system. The operating voltage, continuous current, frequency, short circuit interrupting capability, and time-current coordination needed are some of the factors which must be considered when designing a breaker. Government and industry are placing increasing demands upon the electrical industry for interrupters with improved performance in a smaller package and with numerous new and novel features.
Stored energy mechanisms for use in circuit breakers of the single pole or multi-pole type have been known in the art. A particular construction of such mechanisms is primarily dependent upon the parameters such as rating of the breaker. Needless to say, many stored energy circuit breakers having closing springs cannot be charged while the circuit breaker is in operation. For that reason, some circuit breakers have the disadvantage of not always being ready to close in a moment's notice. These circuit breakers do not have, for example, and open-close-open feature which users of the equipment find desirable.
Another problem present in some prior art circuit breakers is that associated with matching the spring torque curve to the breaker loading. These prior art breakers utilize charging and discharging strokes which are each 180.degree.. The resulting spring torque curve is predetermined, and usually cannot be matched with the breaker loading. Such a predetermined curve mandates that the elements associated with the breaker be matched for this peak torque rather than be matched with the breaker load curve.
Another desirable characteristic in these circuit breakers is to provide an efficient arc chamber to extinguish any arcs present when the contacts move from closed to open positions. The arc chamber should be designed to maximize the interrupting current of the circuit breaker so that higher current ratings can be achieved safely.